Immunogenicity and protection efficacy of recombinant fowlpox virus expressing turkey coronavirus nucleocapsid or spike protein
Abstract
Studies were conducted to determine whether recombinant fowlpox virus (rFPV) expressing turkey coronavirus (TCoV) nucleocapsid (N) or spike (S) protein could induce adequate immune response and provide efficacious protection against TCoV infection. Recombinant fowlpox virus encoding TCoV N gene (rFPV-N) with a titer of 2.6x106 plaque forming unit (pfu)/ml or rFPV carrying TCoV S1 gene (rFPV-S1) with a titer 1.0x107 pfu/ml was generated by transfection of fowlpox virus (FPV) -infected QT-35 cells with FPV vector carrying TCoV N gene. Seven-day-old turkey poults were inoculated once or twice by wing web route with 104, 105 or 106 pfu of rFPV-N or rFPV-S1 or with 106 pfu of rFPV-N and 106 pfu of rFPV-S1 in separate wing at 2-week interval and orally challenged with 100 egg infective dose (EID50) of TCoV two weeks after the second inoculation with the respective rFPV preparation. Significantly (P<0.05) increased stimulation index in lymphocyte proliferation response and significantly (P<0.05) increased nitrite concentration from MQ-NCSU chicken macrophage cells for TCoV N protein-stimulated spleen lymphocytes was seen in the group inoculated once or twice with 10 4, 105 or 106 pfu of rFPV-N or with 106 pfu of rFPV-N and 106 pfu of rFPV-S1 in separate wing at 14, 17 or 28 days (prior to challenge) after the first inoculation with the respective rFPV preparation. Significantly (P<0.05) increased ELISA values to TCoV were detected at 28 days (prior to challenge) after the first inoculation with the respective rFPV preparation in the group inoculated once or twice with 104 or 106 pfu of rFPV-S1 or with 106 pfu of rFPV-N and 106 pfu of rFPV-S1 in separate wing by using the ELISA plates coated with recombinant TCoV N or partial S1 protein. The virus neutralization (VN) titers to TCoV of 1:4 were seen in the group inoculated twice with 104 or 106 pfu of rFPV-S1 or with 106 pfu of rFPV-N and 106 pfu of rFPV-S1 in separate wing prior to challenge. The jejunum and ileum from turkey poults in the group inoculated once or twice with 104, 105 or 106 pfu of rFPV-N or rFPV-S1 or with 106 pfu of rFPV-N and 106 pfu of rFPV-S1 in separate wing had significantly (P<0.05) reduced numbers and intensity of TCoV- specific immunofluorescent enterocytes as compared to those in the challenge control groups 5 days after challenge. In conclusion, rFPV-N that is able to elicit specific cellular immunity and rFPV-S1 that is capable of triggering specific neutralizing humoral immunity can reduce intestinal infectivity against challenge by TCoV.
Degree
Ph.D.
Advisors
Wu, Purdue University.
Subject Area
Horticulture|Virology
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.